In production design of a cigarette, it is necessary to consider various chemical properties and physical properties of leaf tobacco. A filling capacity of cut tobacco is one of the physical properties of the leaf tobacco. The filling capacity is a numerical value of a volume of 1 g of leaf tobacco which has been compressed at a certain pressure for a certain time period after being cut into the form of cut rags. That is, in a case where the filling capacity of cut tobacco is high, it is possible to produce a large number of cigarettes per weight of the cut tobacco. Further, measurement of the filling capacity makes it possible to estimate the number of cigarettes which can be manufactured from 1 kg of cut leaf tobacco. As such, the filling capacity of the cut tobacco is useful for production planning and also allows, in variety development and blending design, selecting and using leaf tobacco which requires a low production cost. Accordingly, the filling capacity of the cut tobacco is (i) an important factor in terms of cost for a raw material as well as (ii) an essential element for the production design.
Near infrared spectroscopy, in which factors such as a transmission absorption spectrum or a diffuse reflectance spectrum of a sample are measured by irradiating a near infrared ray on the sample, allows non-destructive and prompt measurement of the factors and is therefore widely used in various fields.